kernel/linux.git/arch/powerpc/lib/locks.c, branch v6.19.11

powerpc/pseries: Move some PAPR paravirt functions to their own file

2020-07-26T13:34:26+00:00

These functions will be used by the queued spinlock implementation, and may be useful elsewhere too, so move them out of spinlock.h. Signed-off-by: Nicholas Piggin Acked-by: Waiman Long Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200724131423.1362108-2-npiggin@gmail.com

powerpc/spinlocks: Rename SPLPAR-only spinlocks

2019-08-27T03:03:36+00:00

The __rw_yield and __spin_yield locks only pertain to SPLPAR mode. Rename them to make this relationship obvious. Signed-off-by: Christopher M. Riedl Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190813031314.1828-3-cmr@informatik.wtf

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

powerpc: clean the inclusion of stringify.h

2018-07-30T12:48:17+00:00

Only include linux/stringify.h is files using __stringify() Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/spinlock: Fix spin_unlock_wait()

2016-06-14T06:05:44+00:00

There is an ordering issue with spin_unlock_wait() on powerpc, because the spin_lock primitive is an ACQUIRE and an ACQUIRE is only ordering the load part of the operation with memory operations following it. Therefore the following event sequence can happen: CPU 1 CPU 2 CPU 3 ================== ==================== ============== spin_unlock(&lock); spin_lock(&lock): r1 = *lock; // r1 == 0; o = object; o = READ_ONCE(object); // reordered here object = NULL; smp_mb(); spin_unlock_wait(&lock); *lock = 1; smp_mb(); o->dead = true; < o = READ_ONCE(object); > // reordered upwards if (o) // true BUG_ON(o->dead); // true!! To fix this, we add a "nop" ll/sc loop in arch_spin_unlock_wait() on ppc, the "nop" ll/sc loop reads the lock value and writes it back atomically, in this way it will synchronize the view of the lock on CPU1 with that on CPU2. Therefore in the scenario above, either CPU2 will fail to get the lock at first or CPU1 will see the lock acquired by CPU2, both cases will eliminate this bug. This is a similar idea as what Will Deacon did for ARM64 in: d86b8da04dfa ("arm64: spinlock: serialise spin_unlock_wait against concurrent lockers") Furthermore, if the "nop" ll/sc figures out the lock is locked, we actually don't need to do the "nop" ll/sc trick again, we can just do a normal load+check loop for the lock to be released, because in that case, spin_unlock_wait() is called when someone is holding the lock, and the store part of the "nop" ll/sc happens before the lock release of the current lock holder: "nop" ll/sc -> spin_unlock() and the lock release happens before the next lock acquisition: spin_unlock() -> spin_lock() which means the "nop" ll/sc happens before the next lock acquisition: "nop" ll/sc -> spin_unlock() -> spin_lock() With a smp_mb() preceding spin_unlock_wait(), the store of object is guaranteed to be observed by the next lock holder: STORE -> smp_mb() -> "nop" ll/sc -> spin_unlock() -> spin_lock() This patch therefore fixes the issue and also cleans the arch_spin_unlock_wait() a little bit by removing superfluous memory barriers in loops and consolidating the implementations for PPC32 and PPC64 into one. Suggested-by: "Paul E. McKenney" Signed-off-by: Boqun Feng Reviewed-by: "Paul E. McKenney" [mpe: Inline the "nop" ll/sc loop and set EH=0, munge change log] Signed-off-by: Michael Ellerman

cpufreq/ppc: Add missing #include

2015-03-25T05:53:28+00:00

If CONFIG_SMP=n, does not include , causing: drivers/cpufreq/ppc-corenet-cpufreq.c: In function 'corenet_cpufreq_cpu_init': drivers/cpufreq/ppc-corenet-cpufreq.c:173:3: error: implicit declaration of function 'get_hard_smp_processor_id' [-Werror=implicit-funcuresh E. Warrier" X-Patchwork-Id: 443703 Message-Id: <54EE5989.7010800@linux.vnet.ibm.com> To: linuxppc-dev@ozlabs.org Date: Wed, 25 Feb 2015 17:23:53 -0600 Export __spin_yield so that the arch_spin_unlock() function can be invoked from a module. This will be required for modules where we want to take a lock that is also is acquired in hypervisor real mode. Because we want to avoid running any lockdep code (which may not be safe in real mode), this lock needs to be an arch_spinlock_t instead of a normal spinlock. Signed-off-by: Suresh Warrier Acked-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt

powerpc: Add smp_mb()s to arch_spin_unlock_wait()

2014-08-13T05:13:27+00:00

Similar to the previous commit which described why we need to add a barrier to arch_spin_is_locked(), we have a similar problem with spin_unlock_wait(). We need a barrier on entry to ensure any spinlock we have previously taken is visibly locked prior to the load of lock->slock. It's also not clear if spin_unlock_wait() is intended to have ACQUIRE semantics. For now be conservative and add a barrier on exit to give it ACQUIRE semantics. Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix little endian lppaca, slb_shadow and dtl_entry

2013-08-14T05:33:35+00:00

The lppaca, slb_shadow and dtl_entry hypervisor structures are big endian, so we have to byte swap them in little endian builds. LE KVM hosts will also need to be fixed but for now add an #error to remind us. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove FW_FEATURE ISERIES from arch code

2012-03-21T00:16:11+00:00

This is no longer selectable, so just remove all the dependent code. Signed-off-by: Stephen Rothwell Signed-off-by: Benjamin Herrenschmidt

powerpc: various straight conversions from module.h --> export.h

2011-10-31T23:30:44+00:00

All these files were including module.h just for the basic EXPORT_SYMBOL infrastructure. We can shift them off to the export.h header which is a way smaller footprint and thus realize some compile time gains. Signed-off-by: Paul Gortmaker